Prolactin+final

Figure 11-3: Autonomic control centers in the brain [email_address]

HYPOTHALAMUS Integrates functions that maintain chemical and temperature homeostasis Controls the release of hormones from the anterior and posterior pituitary Synthesizes releasing hormones in cell bodies of neurons Hormones are transported down the axon and stored in the nerve endings Hormones are released in pulses [email_address]

Hypothalamic Releasing Hormones Seven releasing hormones are made in the hypothalamus Thyrotropin-releasing hormone (TRH) Corticotropin-releasing hormone (CRH) Gonadotropin-releasing hormone (GnRH) Growth hormone-releasing hormone (GHRH) Growth hormone-release inhibiting hormone (GHIH) Prolactin-releasing factor (PRF) Prolactin-inhibiting hormone (PIH) [email_address]

WHAT IS PROLACTIN? Protein hormone secreted by the anterior pituitary gland, that produces milk in the breast. Synthesized in pit. Acidophils. • Human prolactin is 199 A.A. on chromosome 6. • It does not regulate secondary endocrine glands in humans. [email_address]

WHERE DOES PROLACTIN COME FROM ? E:\prolactin3.jpg [email_address]

HISTORY OF PROLACTIN Around eighty years ago researchers first established that the pituitary gland regulates mammary gland function as demonstrated by the ability of its extract to promote both mammogenesis and lactogenesis in animal models. Prolactin (PRL), contributing to these effects. [email_address]

CONTINUED…. Mid 1930s PRL had been purified as a distinct lactogen. Interest in these hormones initially centered about their potential for increasing milk production, while in the latter half of the twentieth century it became obvious that these hormones also had the potential to influence mammary cancer development . [email_address]

DO MALES HAVE PROLACTIN? Men also have the hormone prolactin. Macroprolactinomas, are large tumors which are commonly found in men. Prolactinomas in men tend to occur in older men and size usually increases before symptoms occur. [email_address]

SYMPTOMS IN MEN Decreased sexual interest Enlargement of breast tissue (gynecomastia) Headache Infertility Vision changes [email_address]

OXYTOCIN EXERTS AFTER…? Suckling stimulates the release of prolactin, which stimluates milk production and release of oxytocin. Oxytocin stimulates contraction of the milk glands. [email_address]

CONTINUED… Milk is squeezed out of the milk gland, into the milk ducts and into the nipple. In the beginning milk is blue (foremilk). After a couple of minutes of feeding, hind milk is produced. Contains more fat and is the main source of energy for your baby. Contains lactose, proteins and small amounts of fat. [email_address]

Immediately after pregnancy Prolactin enhance synthesis of lactose It enhances galactosyltransferase enzyme. Postpartum lactation : High levels of prolactin inhibits LH secretion anovulation amenorrhea With continued nursing, FSH rise, LH remains low Early postpartum period: FSH and LH: low [email_address]

Levels rise in pregnancy Prolactin [email_address]

DOES IT HELP BABIES? Perfect source of nutrition for infants Contains appropriate amounts of carbohydrates, protein, fat. Provides digestive proteins, minerals, vitamins and hormones that infants need. Antibodies from mother also get transferred to baby. [email_address]

COW MILK VS. BREAST MILK Cow milk given to a baby before year 1, may make he/she allergic to diary products. Cow milk has same components as breast milk, but aren’t the same amount as human milk. Mother milk has glucose, as well as iron and cow milk does not. Doesn’t contain antibodies like human milk as well. [email_address]

Prolactin Effects Promotes breast development and synthesis of milk proteins Levels low in absence of pregnancy due to dominant inhibitory effect of dopamine (“prolactin inhibitory hormone”) Note: patients treated with antipsychotics (act at Dopamine receptor antagonists) can exhibit hyperprolactinemia) Has been referred to a “parental hormone” because its injection into animals can produce parental behavioural patterns such as nest-building. Orgasm induces prolactin secretion in human males and females, reduces libido post-coitus. ie sexual refractory period. [email_address]

Prolactin regulation Prolactin is under tonic inhibitory control by the hypothalamus through release of dopamine Increased levels of estrogen in pregnancy induce release of prolactin Suckling overrides dopamine’s inhibitory control through neurogenic signals from the breast. Suckling increases prolactin levels markedly (100 fold increase within 30 min of breast feeding) [email_address]

Increased Prolactin during nursing Increased levels of prolactin in nursing mothers decrease the release of GnRH from the hypothalamus (by negative feedback inhibition) This causes a corresponding decrease in release of LH and FSH (“gonadotropins”) resulting in suppression of ovulation This provides a natural form of contraception while a mother is breast feeding. - GnRH FSH/LH - [email_address]

Prolactin Deficiency [email_address]

Deficiency Deficiency occurs secondary to general anterior pituitary dysfunction. The most commonly associated condition is postpartum pituitary necrosis (Sheehan syndrome); Can also be caused by anterior pituitary impairment secondary to pituitary (or extrapituitary) tumor or treatment of tumor, parasellar diseases, head injury, infection (eg, tuberculosis, histoplasmosis), or infiltrative diseases (eg, sarcoidosis, hemochromatosis, lymphocytic hypophysitis). [email_address]

Pathophysiology Characterized by the inability of pituitary lactotrophs to secrete prolactin and by the resulting lack of puerperal lactogenesis. Other pathophysiologic mechanisms have not been fully established . [email_address]

Prolactin disorders [email_address]

Hyperprolactinemia-evaluation Plasma levels ; 5-27ng/ml throughout normal mens cycles Secreted in pulsatile fashion with pulse frequency ranging from 14/24hrs(late follicular phase) to 9/24hrs(luteal phase) Diurnal variation ; lowest levels occurring in midmorning, rise 1 hr after onset of sleep and continue to rise until peak values reached between 5-7AM Should not drawn soon after patient awakes or after procedures Preferably is drawn midmorning and not after stress, venipuncture, breast exam Prolactin and TSH ; basic evaluation in infertile women [email_address]

Hyperprolactinemia-physical signs Amenorrhea without galactorrhea(ovulation cessation) ; related following gonadal and hypothalamic-pituitary effects ↓ in granulosa cell number and FSH binding , inhibition of granulosa cell 17 b-estradiol production by interfering with FSH action, inadequate luteinizaion and reduced progesterone and suppressive effects of prolactin on GnRH pulsatile release which may mediate most of the anovulatory effects Isolated galactorrhea ; within normal range in nearly 50% of such patients Amenorrhea and galactorrhea 2/3 ; have hyperprolactinemia (1/3 ; have pituitary adenoma) [email_address]

Hyperprolactinemia-imaging techniques In patients with larger micro- and macroadenomas ; higher than 100ng/ml Levels lower than 100ng/ml ; smaller microadenomas and other suprasellar tumors Over 90% of untreated women, microadenomas not enlarge over 4 to 6 yrs period PRL correlate with tumor size but both ↓& ↑ in PRL may occur without any change in tumor size F/U PRL ↑ or central nervous system symptoms(+) -> repeat scanning [email_address]

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